A Gray Level Watermarking Algorithm Using Double Layer Hidden Approach

摘要

Watermarking techniques 1-5 are widely used to protect thesecret document. In some valuable literatures, most of themconcentrate on the binary data watermarking by using comparisons ofan original image and a watermarked image to extract the watermark.In this paper, an efficient watermark- ing algorithm is presentedwith two-layer hidden for gray-level image watermarking. In the firstlayer, the key information is found based on the codebook concept.Then the secret key is further hidden to the watermarked imageadopting the encryp- tion consisting of spatial distribution in thesecond layer.